Manufacture of ferrous alloys



Patented Nov. 28, 1922.

UNITED STATES V 1,437,273 PATENT OFFICE.

HOEATIO ARTHUR SKELLEY AND AN DREW IBBABNER SMITH, OF BATTERSEA, LONDON, ENGLAND, ABSIGNOBB TO CONTINUOUS REACTION COMPANY, LIMITED, 01' LONDON,

ENGLAND.

Illo Drawing.

To all whom it may concern:

Be it known that we, HORATIO ARTHUR SKELLEY and ANDREW 'BRABNER S MrrH, subjects of) the King of Great Britain, re-

5 sidin at 155 Church Road, Battersea, London, W. 11, England, have invented new and useful Improvements in the Manufacture of Ferrous Alloys, of which the following is a specification. I

This invention relates to improvements in the manufacture of ferrous alloys composed of iron and relatively small proportions of chromium, with or without carbon and with or without other metals such as tungsten, molybdenum, vanadium, nickel,

manganese or titanium.

One object of the inventlon is the production in a simple and economical manner of chromium-containing allo s of known types, such as stainless stee and highs d steel. Another object 1s the prodifition of rustless iron, i. e. an alloy of iron and chromium containing little or no carbon.

The invention is based upon the discover that if oxide of iron, in the form of mil scale or the like, be mixed with pulverized silicon or ferrosilicon (containing, say, over 50% Si) and a suitable oxidizing $0 a nt containing nitrogen, such as sodium nitrate, reaction may be initiated at a point in the cold or heated mixture as in the wellknown alumino-thermic rocess and if suitable proportions of the lngredients be used 85 the reaction proceeds to completion, a high yield of iron'practically free from carbon and silicon resulting. By making suitable additions to the mixture, either initially or during the reaction or after reaction has 40 taken place, alloys of the iron with other metals and with or without carbon may be obtained.

According to this invention, therefore, a ferrous alloy composed of iron and a rela tively small proportion of chromium, with or without carbon and with or without other metal or metals, such as tungsten, molybdenum, vanadium, nickel, manganese or titanium, is roduced by the silico-thermic 60 reduction 0 oxide of iron in the form of mill scale, magnetic oxide, ferric oxide or the like,- by means of silicon or ferro-silicon (containing, say, over Si) in the presence of a suitable oxidizin agent containing nitrogen, such as ium nitrate or ums-scrum. or rnimcus ALLOYS.

Application filed Kay 29, 1922. Serial No. 564,617.

suitable bhromium-yielding and if required other ingredlents being a ded to the mixture either initially or during the reaction as the appropriate oxide, to be reduced simultaneously with the oxide of iron. This may be generically referred to as chromiferous material. If it is desired that the resultant alloy contain carbon, the carbon may be added as such to the mixture or may be added as a constit'utent of the chromium or ferrochromium used.

The following examples illustrate the invention: I

1. Stainless s'teeZ.Into a crucible is put a mixture of 100 lbs. of mill scale, 221} lbs. pulverized silicon (or 25 lbs. of ferrosilicon containing 90 per cent Si), 15 lbs. of sodium nitrate and 10% lbs. of crushed chromium (or 16 lbs. of ferrochromium. containing 65 per cent Cr), a quantity of carbon sufficient to ensure the presence of not more than 0.6 per cent thereof in-the resulting alloy being introduced, preferably as a constituent of the chromium or ferrochromium. Preferably 7% lbs. of calcium fluoride, are added to enhance the fluidity of the slag produced. Reaction is initiated as in the aluminothermic process.

I]. High speed stecZ. Into a crucible is put a mixture of 100 lbs. of mill scale, 28?; lbs. of pulverized silicon (or 31% lbs. of ferrosilicon containing 90 per cent Si), 15 lbs. of sodium nitrate, and 21% lbs. of tungsten ore free from tin and other objectionable impurities and containing per cent of WO and 16 per cent of FeO. Preferably 71} lbs. of calcium fluoride are added to enhance the fluidity of the slag produced. Reaction is initiated and 31} lbs. of ferrochromium (containing 65 per cent Cr and 6 er cent carbon) and 6 lbs. ferrovanadium 30 per cent V) are then added to the molten reduced metal. In this example the tungsten in the resultingalloyis produced by the silico-thermic reduction of the tungsten oxide in the ore.

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III. Rustlees ir0n.-The procedure is the same as in the first example above except that the materials employed contain little or no carbon. The invention is particularly suitable for the production of this alloy, which possesses properties of considerable industrial value.

What we claim is 1. The manufacture of an alloy containing iron and chromium by the silico-thermic reduction of iron oxide and chromiferous material in the presence of an oxidizing agent containin nitrogen.

2. The manu acture of an alloy containing iron and chromium by the silico-thermic reduction of iron oxide and chromiferous material in the presence of a nitrate oxidiz- 3. he manufacture of an alloy containin iron and chromium by the silico-thermic re uction of iron oxide and chromiferous material in the presence of carbon and an oxidizing agent containing nitrogen.

4. The manufacture of an alloy containin iron and chromium by the silico-thermic re uction of iron oxide and chromiferous material in the presence of carbon and a nitrate oxidizin agent.

5. The manu acture of rustless iron by silico-thermic reaction in a mixture of 100- as our invention we have signed our names this 17th day of May, 1922.

HORATIO ARTHUR SKELLEY. ANDREW BRABNER SMITH. 

